Blockchain is concerned with moving the crowd from being the source of supply to being the 'intermediary' that actually runs and, implicitly, collectively owns the market itself.

Blockchain is problematic in that because transactions are 'immutable', if an employ were to make a mistake, the company would just have to live with it.
Blockchain is problematic in that processing trades via the technology would not simplify the capital markets, but rather move the complexity around.
Blockchain is problematic in that mistakes might be irreversible, potentially bringing huge losses.
Blockchain is a technology with a tantalising, alchemical prospect: the creation of resolute trust among anonymous and far-flung participants in digital networks... it is a trust-shaped technology just as concerns spike about a deepening trust-shaped hole in public life.
Blockchain is trapped in a paradox. The more likely it is to disrupt the global financial system, the less likely it is to succeed because for disruption to be a positive business force, it must drive new competitive advantage, not simple chaos.
Blockchain is problematic in that moving cash equity markets to a blockchain infrastructure would drive a significant increase of the overall transaction cost.

Blockchain is a Trojan Horse, sent by radical Libertarians to undermine the global financial system.